In the summer of 2011, a Swedish treasure-hunting team was scanning the floor of the northern Baltic Sea with sonar, looking for old shipwrecks. What they found instead was something they could not explain: a roughly circular object, about 60 metres across, sitting some 90 metres below the surface, at the end of what appeared to be a long track on the seabed, as if something had skidded to a stop. The sonar image looked, to many observers, uncannily like the Millennium Falcon from Star Wars. Within weeks, newspapers around the world were calling it a crashed UFO. Fifteen years later, the object has never been independently surveyed, its exact position has never been published, and the argument about what it is has never been settled — because almost nobody has been allowed to look.
The Find
The finders were a small Swedish company of wreck hunters that called itself the Ocean X Team. Its leaders were the professional diver Peter Lindberg and the businessman Dennis Åsberg. Lindberg had previously found the wreck of the schooner Jönköping and thousands of bottles of century-old champagne, which gave the team credibility with the press. On 11 June 2011, nine divers from the team set out to look for more wrecks in the Gulf of Bothnia, the long northern arm of the Baltic Sea that separates Sweden from Finland. They searched with side-scan sonar: a boat tows the instrument behind it on a cable, and it sends sound waves out to both sides, turning the echoes into a flat picture of the bottom, in which anything that sticks up throws an acoustic shadow.
On 19 June 2011, a large round shape appeared on the screen. The team showed the picture to marine scientists in Sweden, and none of them could say what it was. The team estimated the object at about 60 metres across, at a depth of 80 to 91 metres depending on the report, with a height of about 4 metres. Beside it appeared an elongated seabed feature that the team soon began describing as a “track” or “runway,” some 300 metres long. In later surveys the team reported a second, similar anomaly about 200 metres from the first. The team kept the exact position to itself. The only thing it ever gave out was the rough area: in the open sea about halfway between Sweden and Finland.
The Objections
The single sonar image provided by Ocean X drew criticism from a number of sources, and the criticism was technical. Hanumant Singh of the Woods Hole Oceanographic Institution, an underwater imaging specialist, examined the widely circulated image and said it could not be trusted: the sonar instrument used was cheap, improperly wired, and poorly calibrated, and the resulting distortions rendered the image unreliable. Sonar images are not photographs. They are acoustic reconstructions based on how sound waves bounce back to a receiver, and a towed instrument on a long cable introduces disturbances of its own. Ocean X acknowledged that the outer edge of the shape looked jagged partly because the movement of the towed sonar unit had disturbed the image.
The team returned to the site in June 2012 with divers and additional equipment. One diver, Stefan Hogeborn, reported that the object looked like stone that had been cast in cement. The divers also reported that their equipment failed above the object: in a team press release, Hogeborn said the satellite phone and everything electric stopped working, and worked again about 200 metres away. Nobody outside the team has confirmed these failures; they are known only from the divers’ own account.
What the Rocks Said
Samples of stone recovered at the site were given to Volker Brüchert, an associate professor of geology at Stockholm University. His analysis indicated that most are granites, gneisses, and sandstones — ordinary rocks, the kind the great ice sheets of the last Ice Age dragged across northern Europe and left behind when they melted. Swedish geologists Fredrik Klingberg and Martin Jakobsson added that the chemical composition of the samples resembles that of nodules that are not uncommon in sea beds, and that materials found in them, including limonite and goethite, can indeed be formed by nature. The geologists did not have actual samples from the object itself, only from the seafloor and surrounding material — a limitation the critics of the sceptical view have seized on.
The consensus of experts and scientists is that the image most likely shows a natural geological formation, probably a glacial deposit: a big pile of rocks left behind by Ice Age glaciers. That is the leading interpretation, and no peer-reviewed study or official archaeological investigation has produced evidence supporting an artificial origin. But the consensus has a hole in it that keeps the story alive. What the whole formation is, nobody outside the team has been able to measure, because the team that found it still keeps its position secret. As of September 2026, no comprehensive published investigation of the site existed, and no validated new discovery had displaced the glacial interpretation. The anomaly remains, in the strictest sense, unexamined.
What Is Documented, and What Is Not
Documented: In June 2011 the Swedish Ocean X Team, led by Peter Lindberg and Dennis Åsberg, detected a roughly circular sonar feature about 60 metres across at 80–91 metres depth in the Gulf of Bothnia; the team reported a second feature about 200 metres away and a 300-metre track; divers returned in June 2012 and recovered rock samples; Volker Brüchert identified the samples as granites, gneisses, and sandstones; Hanumant Singh of Woods Hole criticised the sonar image as unreliable; the team’s exact position for the site has never been published.
Unverified or disputed: That the feature is artificial or a crashed craft; that electronic equipment failed above the object; the precise size and shape of the formation, which rests on a single disputed sonar image; and the glacial-deposit interpretation itself, which has never been tested by an independent survey of the formation. No independent team has examined the site.